3) Write code that will randomly generate small stereo sound samples. Noise, beeps and buzzes, basically. Status: Not done, but I can do this in Perl or C, no prob.

4) Find or write a program that will take this sound sample, and plot a Lissajous squiggle from it, and save it as a bitmap. Status: Don't know of any program that can do this, but presumably I can write this as well, worse comes to worse. See: http://youtu.be/4zaR6GZvxCY

5) Find an open-source OCR tool that works on the command line. Status: I know such a tool exists, just can't remember the name.

5) Automate the process. Build a script that generates samples, converts them into images, and passes them in machine-gun fashion to the OCR tool. If it turns out the OCR tool thinks the resulting image looks like a number, set that particular sound sample aside, and start building sort of a catalog...a bunch of sounds that look like "4", like "7", etc..dozens of examples of each number in a catalog.

6) Once a large enough catalog of numeral sound samples exists, start "breeding" them, by mixing the audio in different proportions, to yield even nicer-looking numerals. For example, take two sound samples that the OCR engine thought looked like an "8", and mix them 80/20 to see if the resulting sound produces an OCR result that looks better than its parents. Lather, rinse, repeat. Image purity should increase with time.

7) Eventually, this algorithm will produce a set of sound samples that, when played against an oscilloscope in XY mode, will show easily readable numerals. Use this as the basis of a clock, for grins.

8) Package all this on the Arduino/Pi, and fit it inside the oscilloscope, so, that when it boots up, it spends a few hours "teaching" itself how to produce numbers on the display using that script, then goes into its normal clock-displaying mode using what it learned. Perhaps even continue the refinement process in between clock ticks.

The arduino definitely would not have the power to perform this on board (the due may but I don't have experience with that yet) image processing with an arduino requires too much power. The Pi would be a better bet.

Cool idea. Question: how would it determine whether a frequency generates a "better" looking number? If this is subjective it would require attention from the user. Or your could (objectively) compare it bit-by-bit with an existing font.

There is absolutely no need for standalone DACs in this project, nor computer vision, nor "powerful embedded computer".. All that's needed is an Arduino w/ a sound sheild, or a Pi... Anything that can play audio at even mediocre resolution.

Not only are DAC chips unnecessary, they're incredibly slow for the purpose being described here. Even at 12-bit resolution, common pair of DACs like 4725's are barely fast enough to paint and persist a dozen vectors without noticable flicker on the phosphor.

This is where an arduino sheild with decent audio playback resolution or a stock Raspberry Pi comes in. An audio chip performs the same purpose; it modulates voltage on two lines, a Left and a Right channel, and upwards of 44 KHz. X, and Y. It's absolutely feasible to paint lissajous patterns, or even full bitmaps with nothing more than the Audio Out on a soundcard.

Besides...why on earth would I paint the resulting lissajous pattern on a scope, and then scan it with a camera, when I could simply plot it to a bitmap image as I described?

I do want advice. The problem is, I came here asking for advice on a golf swing, and you've recommended I dribble lower to the floor and work on my free-throws.

The scripting i'm referring to would be written on/for the Pi, or offloaded to the system I use for my Arduino development. It's kinda hard to fit a two-channel PCM generator-to-XY-graph-generator-to-OCR engine in 32KB.